Static magnetic field assisted resistive sense element

Abstract

Apparatus and associated method for writing data to a non-volatile memory cell, such as spin-torque transfer random access memory (STRAM). In accordance with some embodiments, a resistive sense element (RSE) has a heat assist region, magnetic tunneling junction (MTJ), and pinned region. When a first logical state is written to the MTJ with a spin polarized current, the pinned and heat assist regions each have a substantially zero net magnetic moment. When a second logical state is written to the MTJ with a static magnetic field, the pinned region has a substantially zero net magnetic moment and the heat assist region has a non-zero net magnetic moment.

1. An apparatus comprising a resistive sense element (RSE) having a free layer separated from a heat assist region by a first barrier layer and from a pinned region by a second barrier layer, wherein the heat assist region has an out-of-plane anisotropy in relation to the free layer and pinned region. 
     
     
       2. The apparatus of  claim 1 , wherein the pinned region comprises a plurality of fixed magnetic layers configured in an anti-parallel orientation. 
     
     
       3. The apparatus of  claim 1 , wherein the pinned and heat assist regions each have a substantially zero net magnetic moment during a read operation. 
     
     
       4. The apparatus of  claim 1 , wherein the spin polarized current passes through the RSE in a single direction. 
     
     
       5. The apparatus of  claim 4 , wherein the spin polarized current passes through a switching device after the RSE. 
     
     
       6. The apparatus of  claim 1 , wherein the heat assist region comprises at least a first synthetic ferri-magnetic layer and a second synthetic ferri-magnetic layer. 
     
     
       7. The apparatus of  claim 6 , wherein the first synthetic ferri-magnetic layer has a lower Curie temperature than the second synthetic ferri-magnetic layer of the RSE. 
     
     
       8. The apparatus of  claim 1 , wherein the heat assist region has a substantially zero net magnetic moment at a first temperature and a non-zero net magnetic moment at a second temperature. 
     
     
       9. The apparatus of  claim 1 , wherein the heat assist region is activated by current induced heat. 
     
     
       10. The apparatus of  claim 1 , wherein the heat assisted region comprises a single ferri-magnetic layer comprising a rare earth transition metal. 
     
     
       11. An apparatus comprising a resistive sense element (RSE) having a free layer separated from a heat assist region by a first barrier layer and from a pinned region by a second barrier layer wherein the heat assist region comprises at least a first synthetic ferri-magnetic layer and has an out-of-plane anisotropy in relation to the free layer and pinned region. 
     
     
       12. The apparatus of  claim 11 , further comprising:
 a first barrier layer between first and second synthetic ferri-magnetic layers; 
 a second barrier layer between the heat assist region and the pinned region; 
 a third barrier layer between the free layer and the pinned region; and 
 a fourth barrier layer between a first pinned layer and a second pinned layer. 
 
     
     
       13. A method comprising:
 providing a resistive sense element (RSE) having a heat assist region, a magnetic tunneling junction (MTJ), and a pinned region; 
 writing a first logical state to the MTJ with a spin polarized current while the pinned and heat assist regions each have a zero net magnetic moment; and 
 writing a second logical state to the MTJ with a static magnetic field while the pinned region has a zero net magnetic moment and the heat assist region is activated to produce a non-zero net magnetic moment. 
 
     
     
       14. The method of  claim 13 , wherein the pinned region comprises a plurality of fixed magnetic layers configured in an anti-parallel orientation. 
     
     
       15. The method of  claim 13 , wherein the pinned and heat assist regions each have a substantially zero net magnetic moment during a read operation. 
     
     
       16. The method of  claim 13 , wherein any spin polarized current passes through the RSE in a single direction. 
     
     
       17. The method of  claim 13 , wherein the heat assist region comprises a plurality of synthetic ferri-magnetic layers. 
     
     
       18. The method of  claim 13 , wherein the heat assist region has a substantially zero net magnetic moment at a first temperature and a non-zero net magnetic moment at a second temperature. 
     
     
       19. The method of  claim 13 , wherein the net magnetic moment of the heat assist region is orthogonal to the MTJ.